Research on non-uniform pressure pulsation of the diffuser in a nuclear reactor coolant pump

Investigation on pressure pulsation and modal behavior of the impeller in a nuclear reactor coolant pump

“…The impeller is excited by the periodic pressure pulsation due to the rotor-stator interaction (RSI) and the impeller itself rotation. Combining this current research and our previous work, 4 the pressure pulsation induced by the RSI near the impeller outlet is the blade-passing frequency (f BPF ) and its higher harmonics, the pressure pulsation acting on the impeller blade is the rotating frequency of the impeller (f R ), the double blade-passing frequency (2f BPF ), the vane passing frequency (f VPF ), and its harmonics. A potentially strong resonance may occur if the frequency of excitation is equal or near to the natural frequency of the impeller and the structural mode matched.…”

“…This grid has been validated in our previous study to explore the characteristics of the unsteady pressure pulsation in the flow passage of the diffuser. 4 As shown in Figure 2, the value of y+ of the whole calculation model except the outlet pipe is lower than 10, which indicates the mesh generation is relatively reasonable. As shown in Figure 3, each channel of the diffuser was marked, and…”

“…The model RCP 4 eighteen monitoring points were arranged on the impeller blade, nine points set on the pressure surface, and nine on the suction surface. The nominal flow rate based on the practical operating condition is chosen for this calculation.…”

“…Transducer locations 4 across their wakes, a hydraulic force caused by the RSI gives regular periodic excitation to the impeller, it consists of various harmonics with the vane passing frequency (f VPF ) and its higher harmonics. 12 From the dominant frequency comparison of the pressure pulsation acting on the impeller, either at the pressure surface or at the suction surface the dominant frequency is f VPF near the outlet while f R near the inlet of the impeller passage.…”

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As the vital component of the nuclear reactor coolant pump (RCP), the impeller plays an indispensable role in driving the coolant in the primary loop in the nuclear power plant. 1,2 The coolant circulation inherently brings flow fluctuation, especially pressure pulsation induced by the rotor-stator interaction, 3,4 and therefore, flow-induced vibration exists, which has a considerable impact on the impeller. Moreover, for the RCP in the actual operation, the impeller operates at a high-temperature, high-pressure, high-radiation, and nonstop environment.

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